Sequring TPS Fedora4

This is my first linux webserver, so new questions come up all the time

I`ve now been running this setup on one server for two monts, and just installed another one for about a week ago.

The setup is basicly unchanged from the tutorial, how sequre is this?.

The question is now how do I sequre the server form attacks.
-I vould like to get logs on attacks etc from the server daily.
-I vould like to proteckt ssh etc from brute force.
-Sugestions on modifications from the default setup to make it more sequre.
-And anything alse to make it fortnox....

What is the max e-mail size in postfix as standard, how tho change this.....

Well, quite many questions....
It sums up to, how do I sequre my server so it don`t get hacked (I know it can`t be 100% sequre),

-I see the server gives output on telnet...
Should i just shut down telnet....
I can`t think of anything I need it for?
It just gives away information on the software I`m running on my server, and gives the hacker a head start?
-Is there any online scanners for testing my server?
-Is there a limit for how many e-mail adresses one can have under one domain?

Port 21 (tcp) is open (ftp)!
Port 25 (tcp) is open (smtp)!
Port 53 (tcp) is open (domain)!
Port 80 (tcp) is open (http)!
Port 81 (tcp) is open (unknown)!
Port 110 (tcp) is open (pop3)!
Port 111 (tcp) is open (sunrpc)!
Port 143 (tcp) is open (imap)!
Port 443 (tcp) is open (https)!
Port 631 (tcp) is open (ipp)!
Port 783 (tcp) is open (unknown)!
Port 953 (tcp) is open (rndc)!
Port 993 (tcp) is open (imaps)!
Port 995 (tcp) is open (pop3s)!
Port 3306 (tcp) is open (mysql)!
Port 5335 (tcp) is open (unknown)!
Port 41318 (tcp) is open (unknown)!
Port 42141 (tcp) is open (unknown)!
Port 43025 (tcp) is open (unknown)!